Pathogenic variants (disease-causing) in the ATM gene are linked to a moderate increase in cancer risk, most notably breast cancer. Women with an ATM mutation have an estimated 20–40% lifetime risk of breast cancer, which is higher than the general population. There is also evidence of increased risks for pancreatic, colon, stomach, and possibly prostate cancer. Management of ATM–related tumor risk includes regular surveillance tailored to guidelines for the ATM gene. ATM variants are not known to be more common in the Ashkenazi Jewish population.
Pathogenic variants in ATM exhibit autosomal dominant inheritance. This means there is a 50% chance the condition can be passed from generation-to-generation. First degree relatives (parents, siblings, children) have a 50% chance to have the same pathogenic variant whereas second degree relatives (grandparents, aunts/uncles, nieces/nephews, half-siblings) have a 25% chance. More distant relatives have lower chances of having the same pathogenic variant when one is identified in the family.
In addition, when an individual inherits pathogenic variants in both copies of the ATM gene, they can develop a condition called ataxia telangiectasia. Ataxia telangiectasia is characterized by progressive cerebellar ataxia (causing poor coordination, unsteady walking, slurred speech, and trouble with fine movements), oculocutaneous telangiectasias (red lesions on the skin and in the eyes), immunodeficiency (impaired immune system function), and increased cancer risk. Ataxia telangiectasia deficiency exhibits autosomal recessive inheritance. This means that both parents must have a single pathogenic variant in the ATM gene to have a 25% chance to have a child with the condition.
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Written December 2025
